Subject: Re: linux-next: build failure after merge of the mm tree

From: Michael Ellerman <[email-masked]>
Date: Tue, 22 Aug 2023 17:12:55 +1000

Matthew Wilcox <[email-masked]> writes:
> On Tue, Aug 22, 2023 at 09:55:37AM +1000, Stephen Rothwell wrote:
>> In file included from include/trace/trace_events.h:27,
>>                  from include/trace/define_trace.h:102,
>>                  from fs/xfs/xfs_trace.h:4428,
>>                  from fs/xfs/xfs_trace.c:45:
>> include/linux/pgtable.h:8:25: error: initializer element is not constant
>>     8 | #define PMD_ORDER       (PMD_SHIFT - PAGE_SHIFT)
>
> Ummm.  PowerPC doesn't have a compile-time constant PMD size?

Yeah. The joys of supporting two MMUs with different supported page
sizes in a single kernel binary.

> arch/powerpc/include/asm/book3s/64/pgtable.h:#define PMD_SHIFT  (PAGE_SHIFT + PTE_INDEX_SIZE)
> arch/powerpc/include/asm/book3s/64/pgtable.h:#define PTE_INDEX_SIZE  __pte_index_size
>
> That's really annoying.  I'll try to work around it.

Sorry, thanks.

cheers